Lubricant for water-reduced belt lubrication

ABSTRACT

The invention relates to a chain lubricant or belt lubricant, having a silicone oil, a multifunctional amine and at least one additive, selected from the group consisting of anionic, nonionic, cationic and/or amphoteric surfactants as an emulsion in an aqueous phase. This is an amine selected from amine salts in which the cation comprises primary, secondary, tertiary and/or quaternary amines and the anion as an organic group has a molecular weight greater than 350, preferably greater than 400. The invention also relates to a method for the water-reduced lubrication of conveyor belts for bottles, cans, other containers and boxes, wherein said chain lubricant or belt lubricant is applied to the surface of the conveyor belt at intervals as an emulsion in an aqueous phase together with added water of less than 30 vol %, preferably less than 20 vol %. The invention also relates to the use for water-reduced lubrication of conveyor belts made of metal or plastic for a very broad field of applications.

The invention relates to a chain lubricant or belt lubricant, a method for the water-reduced lubrication of conveyor belts for bottles, cans, other containers and boxes, and the use of the chain lubricant or belt lubricant for the water-reduced lubrication of such conveyor belts.

Belt lubricants, which are also referred to as chain lubricants, serve the transportation of glass bottles or cans, including beverage cans, other containers and boxes, on conveyor belts. In recent times bottles made of plastic, here preferably of polyethylene terephthalate, known as so-called PET bottles, are also to an increasing degree transported on the conveyor belts.

The belt lubricants or chain lubricants should as a rule feature emulsifying, cleansing and corrosion inhibiting properties. In the field of the beverages industry there are imposed specially high standards of hygiene for this.

Here the smooth running of the transportation of bottles is of great importance in a bottle-filling plant. Should faults arise here it can lead to the stoppage of the entire filling line and thus cause high downtime costs. The belt lubrication is thus of great importance for preventing such faults. The belt lubrication should ensure a smooth functioning of the installation and at the same time keep to a minimum the signs of wear both on the transport system(s) and on the bottles. And at the same time this should not cause an excessive rise in the operating costs, rather these should be kept low.

It is at the present time the usual practice to use belt lubricants greatly diluted with water. Here the preparation of the belt lubricant solution takes place by a dosing by volumetric proportion of the belt lubricant in a stream of water in a central dosing unit. The solution is then fed to nozzles and from there sprayed out as evenly as possible.

The conveyor belts themselves can be made of steel or plastic (synthetic material). Basically it is possible to convey bottles made of glass or plastic, cans, crates, barrels and cardboard boxes.

A basic problem in the transportation plants is posed by the deposits laid down in the piping systems, nozzle fittings, nozzles and sieves. Moreover one may observe a problematic build-up of foam and streaks when using the belt lubricant highly diluted in water.

And there is a special problem caused by the costs of the considerable quantities of fresh water supply and waste water disposal, which inevitably arise due to the high degree of dilution of this belt lubricant which is commonly used for wet-belt lubrication.

Therefore in the prior art one also knows of attempts which aim at replacing the concept of wet-belt lubrication by a dry-belt lubrication.

Dry-belt lubricants require basically no water, and so can be used without the problem of a troublesome build-up of foam, and what is more are also independent of the water hardness.

Thus in EP-B-1 204 730 a composition of lubricant is revealed which is to be used as “dry” lubricant. This composition has the feature that it contains an oil which is selected from silicone oils, oils of plant origin, and/or mineral oils, which are dispersed in an aqueous phase.

It can be used to lubricate the surface of a conveyor belt which is used for the transportation of glass, plastic or cardboard containers. Here the conveyor belts can be made of a synthetic material such as polyacetal or polyamide. Furthermore it is said that the lubricant compound can also be used with certain types of containers on steel, that is to say metal, tracks.

Even though the type of container is not described in detail, it is known in the relevant professional circles that a dry-band lubrication for the transportation of glass bottles on metal tracks has not hitherto been possible in a satisfactory way.

Regarding the silicone oils used, the use of polydimethylsiloxanes with viscosities in the range 1,000-30,000 mPa s (cSt) is said to be suitable. In the example embodiments a silicone oil with a viscosity of 2,000 cSt is used.

WO-A-2008/121720 deals very thoroughly with the problem of belt lubrication on the basis of oil emulsions in an aqueous phase. Here the oil emulsion is produced as a macro-emulsion. It can be either an oil-in-water emulsion or a water-in-oil emulsion. According to this particular applicant, all natural and/or synthetic oils without exception are suitable for such an emulsion. The natural oils here are e.g. animal oils, plant oils, mineral oils, while crude oils are specially named separately again, and such oils which are derived from coal or oil slate. According to the revelation of this prior art, synthetic oils can be such as are synthesised from raw materials which form blocks of larger and/or smaller molecules when they are brought together to react, and then form liquids in a temperature range of about 0-50° C. A wide range of possible oils coming under this definition, from the most varied fields of organic chemistry, are then listed. Here the group of silicones in a wide range of viscosities from 1 cSt-10,000 cSt at 25° C. is also named among others, and dimethyl siloxanes are mentioned as one such possible lubricant.

Additives can be added to this oil emulsion. These include dispersion agents, emulsifiers, surface-active substances, agents for preventing or restricting the contamination of a belt lubricating system by microbes, and agents for the reduction of biofilms, agents for preventing corrosion due to stress cracks, solvents for thinning, and hydrotropic agents as solubilisers. Amines or amine compounds have found a very varied field of use in chemical engineering. Thus basically the use of a great variety of amines or amine compounds is known in all the mentioned groups of additives. These are also listed along with the naming of a whole series of possible compounds, according to this prior art. Thus for example in the field of agents for reducing biofilms in a belt lubrication plant, chelators, such as EDTA and EGTA, are mentioned. Generally EDTA occurs here as the disodium salt of ethylenediaminetetraacetic acid. The ethylenediaminetetraacetic acid anion has a molecular weight of about 292.

Furthermore, from WO-A-2007/149175 there is known a method for lubrication between containers and a conveyor belt, which relates specially to the conveyance of thermoplastic containers in the form of PET containers or bottles, and which here proposes in particular the use of a silicone oil with a viscosity of less than 50 cSt, most preferably of less than 5 cSt, for solving the problem of the stress cracks.

Starting from this prior art, the present invention thus has the objective of preparing a lubricant compound which is also, and in particular, suitable for the transportation of glass bottles on metal tracks, and which avoids the enormous water consumption of the wet-band lubrication, without necessitating an expensive conversion of the installation for this.

This objective is solved according to the invention by a chain lubricant or belt lubricant with a silicone oil, a multifunctional nitrogen compound in the form of an amine and at least one additive, selected form the group consisting of anionic, non-ionic, cationic and/or amphoteric surfactants as an emulsion in an aqueous phase, where the amine is selected from amine salts in which the cation comprises primary, secondary, tertiary and/or quaternary amines, and the anion as an organic group has a molecular weight greater than 350, preferably greater than 400.

By a multifunctional nitrogen compound in the context of the present invention one means a nitrogen compound where more than two functional groups are present in the whole molecule. This multifunctional nitrogen compound forms, or is contained in, the cation of the inventive belt lubricant.

The multifunctional amine as cation of this salt can basically be a primary, secondary, tertiary and/or quaternary amine. In connection with the present invention, one can name in particular, but not exclusively, amine salts on the basis of fatty acids, such as those with lauryl, myristyl, cetyl and stearyl groups. One can also mention fatty amines, such as alkyl propylene diamine, alkyl propylene triamine and other alkyl propylene polyamines.

As anion of this amine salt, which does not itself have any amine or amine compound, there is included an organic group with a molecular weight greater than 350, preferably greater than 400, and specially preferred greater than 500. Test results have shown that the high molecular weight anion has a positive effect on the lubricant effect. It has also been shown that the special lubricant effect of the inventive chain lubricant or belt lubricant results from a synergistic interaction of the multifunctional nitrogen compound in the form of the amine salt, and the silicone oil.

In the case of the surfactant, which is included as at least one additive, possible candidates for the anionic surfactants are basically alkylbenzene sulfonate (ABS) and fatty alcohol sulphate as well as secondary alkane sulfonate (SAS). Regarding ABS and SAS, one should mention their property that they can be used without any problems even with hard water. Besides this these surfactants are characterized by good wetting properties. According to one design variant of the inventive belt lubricant, at least one of the surfactants included in the belt lubricant can itself be the organic group as anion of the amine salt.

Apart from the said advantages of ABS and SAS, the non-ionic surfactants are, however, to be rather preferred, of which in particular the polyalkylene glycol ether or fatty alcohol ethoxylate, fatty alcohol propoxylate and alkyl phenol ethoxylate are to be named as examples.

Other possible additives are the addition of a weak acid in small quantities as solubiliser, a fragrance and/or possibly also a colouring and preservatives.

The inventive chain lubricant or belt lubricant features a very good compatibility of materials, including that in relation to the usual print colours on cardboard packaging; it is low foaming, and independent of the local water hardness. It has in particular excellent transportation properties for glass bottles on metal tracks.

According to a preferred embodiment, the silicone oil may be selected from among polyalkyl, polyaryl, and/or polyalkyl-/polyaryl siloxanes, as well as mixtures of these. In the case of these polysiloxanes, regarding the polyakyl siloxane one can mention polydimethylsiloxane as the most well-known and most suitable polysiloxane, as a linear polysiloxane. Among the polyaryl siloxanes there is diphenyl siloxane, and then in particular phenylmethyl siloxane as one of the polyalkyl/polyaryl siloxanes should be mentioned as suitable. And also amino-functional silicone oils can be mentioned.

Among the inventive lubricants, according to another embodiment the silicone oil has a viscosity of 200-70 cSt, preferably 180-80 cSt, specially preferred is 120-90 cSt, in each case at room temperature.

It is surprising that silicone oils with a low viscosity were found to be specially suitable for the use in belt lubrication, since it is known that the siloxanes are more highly volatile the lower the viscosity.

Thus in our own tests silicone oils with a viscosity of 50 cSt or less were found to be difficult to handle. In practice, in particular a silicone oil with a viscosity in the range of about 100 cSt has proved to be specially well suited here.

The inventive chain lubricant or belt lubricant preferably has a pH value of between 6 and 8.5, preferably a pH value between 6.5 and 8.0.

According to a specially advantageous embodiment the inventive composition has 5-95 wt % (percent by weight) aqueous phase, 0.01-30 wt % silicone oil, 0.01-40 wt % of the multifunctional amine compound in the form of a primary, secondary, tertiary and/or quaternary amine, and 0.01-25 wt. % surfactant. Here the percent by weight of the surfactant can also coincide with that of the amine compound if the organic group as anion of the amine salt is a surfactant.

The invention also relates to a method for water-reduced lubrication of conveyor belts for bottles, cans, other containers and boxes, in which the advantages of the chain lubricant or belt lubricant which have been described above in connection with various embodiments, come specially to bear.

According to the inventive method the said chain lubricant or belt lubricant is applied at intervals to the surface of the conveyor belt as emulsion in aqueous phase together with the addition of water at less than 30 vol % (percent by volume), preferably less than 20 vol %. Here the aqueous phase mentioned in connection with the emulsion, and that of the required addition of water, also referred to as additional water content, are to be strictly distinguished from each other.

A special advantage of the inventive chain lubricant or belt lubricant consists precisely in being able to save on a considerable portion of the water quantity which is usually used and needed in the conventional wet-belt lubrication, when using the inventive method. Thus within the context of the present invention the water quantity used and needed for the wet-belt lubrication serves as reference value of 100%. So the additional portion of water which is now needed and used in the inventive water-reduced lubrication is accordingly presented as a fraction of the water quantity that is used in the wet-belt lubrication. An addition of water of less than 30 vol %, preferably less than 20 vol %, thus corresponds to a water savings of more than 70 vol %, preferably more than 80 vol %. Here the inventive method requires that there always has to be some addition of water, so it cannot be reduced to 0 vol %.

Ideally the water savings amount to 70-85 vol %, although 85-95 vol % would be even more preferable. Depending on the type of plant, at a water savings of about 85 vol % or slightly above this, a point is reached at which the dosing equipment, such as is used in the field of wet-belt lubrication, cannot be used as it is, and a conversion of the installation becomes necessary. This is due partly to the high pressure with which the belt lubricant has to be applied to the conveyor installation in the field of dry-belt lubrication, in order to ensure a sufficient quantity of the belt lubricant or chain lubricant on the conveyor belt. And then the volumes which have to be applied are much lower, because only small or extremely small quantities of the belt lubricant are needed. Due to these small pumped quantities much smaller pumps are needed and this entails the need for a conversion of the installation.

In various tests, even for a water reduction of 70-40 vol %, and even 40-30 vol %, it was possible to achieve a good belt lubrication combined with a water reduction that is still sufficient from the economic standpoint. Thus the plant can certainly continue to be used without conversion, because the pump performance for dosing the belt lubricant has proved to be sufficient in the case of such a water reduction.

It is necessary to distinguish between the concentration of the inventive emulsion itself in its aqueous phase, and the water added when using the belt lubricant on the conveyor belt. Here it is advantageous to have a concentration of the emulsion in the aqueous phase of 2.5-15 wt %, preferably 2.5-7 wt %, specially preferred 3-5 wt %,

The concentration ranges referred to are, it is true, higher than those usually used in the field of wet-belt lubrication. However, this fact can be more than compensated for by the considerable savings in water consumption.

In carrying out the inventive method it has, further, been found to be specially economical if the application of the chain or belt lubricant is done in intervals of a number of seconds, with pauses between the application intervals of a number of minutes. In this way the quantity of the chain or belt lubricant required is reduced.

The invention likewise relates to the use of the chain lubricant or belt lubricant which has been described in various embodiments, for the water-reduced lubrication of conveyor belts for bottles, cans, other containers and boxes in the beverage and foodstuffs processing industry, and in the cosmetics and pharmaceutical industries.

Here the bottles, cans, other containers or boxes can be made of any desired material, selected from glass, plastic, cardboard or metal. Here it is in particular possible, and thus to be mentioned, that the conveyor belt can be designed in metal, and the contact with the container material glass takes place smoothly, in particular also without any specially observed abrasive material wear of the conveyor belt.

Basically the inventive method can be used as desired for the lubrication of conveyor belts made of metal or plastic.

In what follows the invention will be described in more detail using example embodiments.

EXAMPLE 1

The lubricant compound (mixture) is produced as an emulsion, with the figures for the quantities referring to wt % unless stated otherwise.

The products WEICO® COR and STERONAL-GR are used as components of the compound, which are available in the trade from the company Tensid-Chemie GmbH in Muggensturm, Germany.

Together with these a silicone oil in the form of a polydimethyl siloxane, a nitrogenous compound on the basis of alkyl amine salts, which are used as corrosion-inhibitors, and a surfactant as emulsifier, are used. For the rest a small proportion of organic acids is included to adjust the pH value. Where necessary acetic acid, for example, can also be added to adjust the pH value. The pH value of the emulsion produced in this way was set at about 7.6. The viscosity lay in the range of approx. 100 cSt.

The emulsion was produced and used with the STERONAL-GR and WEICO® COR mixed in the proportions 80-20, each in the aqueous phase.

1st Application:

The emulsion produced in the way described in Example 1 was in this test run used as 3% solution diluted in water for the water-reduced belt lubrication of metal belts which were intended for use in conveying glass bottles. The emulsion was applied to the metal conveyor belts, in the present instance made of stainless steel, by spraying in combination with an additional water component of 15 vol %. Serving as the reference figure (100%) for the additional water component used in this way, here and in what follows, is the quantity of water which is usually used in the context of the conventional wet-belt lubrication.

Besides the application by spraying, every other well-known application method, for example brushing on, is also suitable. As a rule the conveyor installations are fitted with automatic application equipment.

For each lubrication of the conveyor or transportation belts of an installation, which was set up for a run of about 20-30,000 bottles per hour, approx. 5 to 12 ml of belt lubricant of the type described in Example 1 was used up, demonstrating that a very economical use requiring only small quantities is possible.

The application of the inventive belt lubricant was carried out at intervals, with an application in this test lasting about 3 sec followed by a pause of about 20 min. Only then was each new application made. This is in contrast to the wet-belt lubrication which can also be carried out continuously.

2nd Application:

The emulsion produced in the way described in Example 1 was, in this test run, applied as 7% solution diluted in water for metal belts for the conveyance of glass bottles. The emulsion was again applied by spraying, combined with an additional water component of 20 vol %. The conveyor installation was set up for the passage of about 80,000 bottles per hour. In each case about 8 to 15 ml of the prepared emulsion were used for the lubrication of the conveyor belts.

The application of the inventive belt lubricant was carried out at intervals of 10 sec each, pausing for about 20 min after the particular application. Only then was a new application carried out.

3rd Application:

The emulsion prepared as described in Example 1 was in this test run applied as 5% solution diluted in water, for the water-reduced belt lubrication of plastic belts which were intended for transporting 0.5 l PET bottles. The emulsion was applied to the conveyor belts by spraying in combination with an additional water component of 15 vol %.

Here too, the work was done in an installation which was set up for the passage of about 20-30,000 bottles. Approx. 5 to 12 ml of the prepared emulsion were used in each case for the lubrication of the conveyor belts, which shows that the application for this purpose too can be done very economically.

The application was again done after an interval of about 20 min each time. One application lasted about 3 sec.

The stress-crack corrosion was determined by referring to the work instruction CC (the so-called Coca-Cola standard): Additives-Line Simulation; Version 1.0 dated 15.10.98. Table 1 shows that basically no stress-crack corrosion could be found:

TABLE 1 Test of compatibility with CC reusable PET bottles Base Area (Floor) Radial Base (Wall) Leakage Nr. 0 A B C D 0 A B C D Yes No Ref. X X X Ref. X X X 1 X X X 2 X X X 3 X X X 4 X X X 5 X X X 6 X X X 7 X X X 8 X X X 9 X X X 10 X X X 0 - no stress-crack corrosion at all A - minor, very superficial cracks B - slight superficial cracks C - major moderately deep cracks D - major deep cracks

4th Application:

By carrying out this test it was possible to compare the conventional wet-belt lubrication to the inventive water-reduced belt lubrication.

The emulsion prepared as described in Example 1 was in this test run applied as 2.5% solution diluted in water. It was tested on metal belts for the transportation of glass bottles in a brewery. The installation was fitted with 53 and 190 nozzles, with a throughput of 9,500 and 30,000 bottles per hour respectively. The emulsion was again applied by spraying.

The application was again done in intervals after about 20 min each time. The application time was 5 sec. Table 2 presents a summary of the test results.

TABLE 2 Comparison of wet-belt lubrication with the inventive water-reduced lubrication Number of Nozzles 53 190 Wet-belt lubrication Water consumption 360 675 previously (l/h) Product consumption 0.9 1.59 previously (kg/h) Solution/nozzle/h 6.8 3.6 Water-reduced belt lubrication Water consumption 29 101 afterwards (l/h) Product consumption, 0.65 2.19 belt lubrication Solution/nozzle/h 0.56 0.54 Savings in −92 −85 water (%) Savings in product (%) −28 38 Performance (bottles/h) 9,500 33,000 Chain material Stainless steel Stainless steel Container Glass bottles Glass bottles (0.5, 0.33) (0.5; 0.33) Coeff. friction (0.5 norm.) 40-45 g 40 g Type of operation Brewery Brewery

5th Application:

All tests of the 1st to 3rd applications were repeated, in their respective forms described above, but the installation was left standing for a whole week unused and uncleaned, after each of the test runs of the 1st to 3rd applications that were carried out. The installation still ran smoothly and without any faults.

In the 3rd application the stress-crack corrosion was again determined using the requirements of the Coca-Cola standard which is known in the industry and which serves as a basis for evaluation. Even here there was no stress-crack corrosion to be found.

Overall a savings in water of between 70 and 85% resulted in all the tests that were carried out.

EXAMPLE 2 Comparison with the Dry-Belt Lubricant Known to Prior Art

The dry-belt lubricant available in the trade under the label “DryExx” by the firm Ecolab Deutschland GmbH, which likewise contains a silicone oil, but no poly-functional nitrogen compound, was tested at the test centre pilot plant. For this purpose several glass bottles were transported on a stainless steel belt. Concentrations of 2.0% and 10% of the said belt lubricant concentrate were used.

In various passes no good lubricant effect was found, and moreover no practical difference between the two different concentrations used. Both the conveyor belt and the bottles on it moved in a very uneasy way. The bottles moved very jerkily and often toppled over.

This experiment showed that the dry-belt lubricants commonly available on the market are not suitable for the transportation of glass bottles on metal tracks in the conditions of water-reduced belt lubrication or belt-lubrication performed without the addition of water.

In the inventive water-reduced belt lubrication itself, however, a considerable quantity of the valuable resource water is saved, without endangering the optimum lubrication effect and thus a smooth transportation of the containers.

It was demonstrated that in the case of the applications in Example 1, it was even possible to partly enhance the smooth transportation by a lowering of the coefficient of friction. 

1. A chain lubricant or belt lubricant, having a silicone oil, a multifunctional amine and at least one additive, selected from the group consisting of anionic, non-ionic, cationic and/or amphoteric surfactants as an emulsion in an aqueous phase, where the amine is selected from amine salts in which the cation comprises primary, secondary, tertiary and/or quaternary amines, and the anion as an organic group has a molecular weight greater than 350, preferably greater than
 400. 2. A chain lubricant or belt lubricant according to claim 1, characterized in that the organic group as an anion of the amine salt is a surfactant. 3.-11. (canceled) 